This section describes background subject matter related to the disclosed embodiments of the present invention. There is no intention, either express or implied, that the background art discussed in this section legally constitutes prior art.
The conventional vacuum-based material deposition methods (CVD, ALD, PVD, etc.) are expensive and slow. Mass production of devices for high volume applications, like Solar cells, LEDs and Data storage media require lower cost high throughput processing. Other conventional material deposition methods, like spin-coating or immersion-coating are not practical for processing large substrates areas.
Some unconventional techniques for material deposition have been explored and demonstrated:
Inkjet printing technique can deposit various materials on variety of substrates inexpensively. Unfortunately, currently resolution of Inkjet printing is limited to >10 um and a drop placement accuracy +/−10 um, which is few orders of magnitude larger that required for emerging applications of Solar cells and LEDs efficiency enhancements or next generation Data storage patterned media application.Wang et al suggested surface energy assisted inkjet printing, which uses surface energy patterns (templates) to improve resolution of inkjet printing. He used Self-assembled monolayers (SAMs) deposited from a vapour phase and patterned using E-beam lithography as a template. This work demonstrated polymeric material deposition with lines as thin as 500 nm. Vapor phase deposition of SAMs and E-beam writing require vacuum systems, which makes this approach costly. Moreover, E-beam method of pattern generation is very slow.
Another emerging technique, microcontact printing (uCP), discussed by Xia et al, uses the relief pattern on the surface of a PDMS stamp to form patterns of self-assembled monolayers (SAMs) on the surfaces of substrates by contact. Then conventional material deposition methods (CVD or spin-coating) are used to deposit functional materials on the surface using such SAM template, as for example, discussed by Clem et al. Similar scheme, suggested by Kagan et al, where conventional material deposition methods over SAM template are spin-coating or immersion-coating.
Obviously, CVD (vacuum methods) are quite expensive. Moreover, cost of equipment and processing grows exponentially with the size of substrate to be processed, so becomes not economical for processing of large areas of substrate materials, like Glass Solar glass panels, architectural windows, Flat panel displays, etc.
It is clear also that conventional non-vacuum methods, like spin-coating and dipping, are not practical for large area material deposition systems.